Not a lot of story to it...
Story: It starts out you wake up in a cryotube. and you try to escape. Not really a story unlike the Bungie games. Just mindless shooting grunts and elites.
Graphics: It is dated by todays standards. It is a fan made game so you can`t expect a lot.
Gameplay: You have two guns like the game. And it is all in 2D. I thought aiming was kinda difficult for someone who plays the xbox and xbox 360 games like me. And the checkpoints take a while to get to. Even for people who play PC.
Online play: I`m guessing online gaming was always dead and still is. I don`t know this for sure though.
Halo Zero is not a bad game at all. It is a good fan made and is not nearly as good as the other Halo games. on PC and Xbox and 360.
And the game is free so you might as well try it.